Verified Solution • 2025–26 Session moderate

QJEEM21Ph8577: JEE Main 2021 Physics - Class 12 JEEM21Ph8577 Solution: Figure A and B shown to long straight wires of circular…

Figure A and B shown to long straight wires of circular cross-section (a and b with a < b), carrying current I which is uniformly distributed across the cross-section. The magnitude of magnetic field B varies with radius r and can be represented as :

JEE Main 2021 (Online) 27th July Evening Shift Physics - Magnetic Effect of Current Question 113 English

Multiple Choice Options

  • A https://ik.imagekit.io/novatra/photos/027b82e52609de6fd0e6ea45adfb39bcbbe9099830a88828ca32b34af13de057.webp
  • B https://ik.imagekit.io/novatra/photos/37bf5f755566100b1ad3963ac9e9289f207d902b1692f1c3a2fa43657fc373f9.webp
  • C https://ik.imagekit.io/novatra/photos/dbaa53d0021ec1eced4abfb9804f81b305fb26044e9d93fcf3ff83a611b42a36.webp
  • D https://ik.imagekit.io/novatra/photos/42b4aec9dcfda3ebd58a69e5e70ca63e8f22b10678174754312e7f315b59d684.webp

Step-by-Step Verified Solution

Graph for wire of radius R :

JEE Main 2021 (Online) 27th July Evening Shift Physics - Magnetic Effect of Current Question 113 English Explanation
As b > a

Ba > Bb

Ba=μ0i2πa{B_a} = {{{\mu _0}i} \over {2\pi a}}

Bb=μ0i2πb{B_b} = {{{\mu _0}i} \over {2\pi b}}

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